Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
The image is a remix of "edo pattern-samekomon".I changed the color of dots from black to white and added BG in light-yellow.
Source Yamachem
A seamless pattern formed from background pattern 102
Source Firkin
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
There are many carbon patterns, but this one is tiny.
Source Designova
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
From a drawing in 'Real Sailor-Songs', John Ashton, 1891.
Source Firkin
Prismatic Abstract Geometric Background derived from an image on Pixabay.
Source GDJ
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
Source Firkin